UFO Sighting in New Rochelle, New York on August 24th 1977 – Heard humming sound looked up to see extreme purple & green/white lights in circle. Hovered then shot straight up and disappeared

I was with 2 friends, we had just arrived home and were walking up the path to my front door. We were 15 years old and it was late summer of 1975. I was looking for my house key when we heard a humming sound and saw an intense light over head. We looked up to see a round aircraft with purple and green bright lights hovering. We had no idea what the object was but were sure it was some type of UFO. It was not like anything we had ever seen or could explain. The noise it made and the colors made it clear that it was not an airplane or helicopter. None of us said anything or moved and within a minute the aircraft lifted up and disappeared completely out of sight. We ran up the steps and pounded on my brother's window to let us in. I tried to tell my parents the next day but they thought we were making it up. We never spoke about it again. I am now 53 and called on of my friends about 6 months ago to ask her if she remembered the event. To my total shock she said she had no recollection so I thought I was crazy. I described this event to a friend who happened to catch the tv show and called me to turn it on. I couldn't believe it when I realized I was not crazy as some kids on Long Island saw exactly what I saw in the summer of 1977 and they went on to explain that sometimes people do not have any memory of this happening!!!